[SOLVED] problem with spice analysis of an op-amp: nested miller

[nanock]

hi friends,
i just encountered a problem in analyzing an OP-AMP named:
"A 100MHz 100dB Operational Amplifier with Multi-path nested miller compensation structure" by "Ruud G. H. Eschauzier, Leo P. T. Kerklaan, Johan H. Huijsing".
i will be wondering if you know the DC analysis and guide me through this project?
also the problem is on transistors' ,named "Q800 till Q850", base and collector current. it's s.th. strange.
well, i just need an emergency help!
kind regards,

 

[leo_o2]

What's your exact problem?
Pls use spice tools to have DC sweep to obtain various DC operating point.

 

[nanock]

hi,
I'm sorry if i couldn't to tell the exact problem.
The op-amp i mentioned above,A 100MHz 100dB Operational Amplifier with Multi-path nested miller compensation structure" by "Ruud G. H. Eschauzier, Leo P. T. Kerklaan, Johan H. Huijsing,
seems to have problem on its current source,q800-q850. The base current is larger than the collector.
So, do you know how could i solve it?

---------- Post added at 11:06 ---------- Previous post was at 11:01 ----------

Hi,
This is the DC sweep results of current source:
"

subckt
element 0:q840 0:q850 0:q820 0:q830 0:q800 0:q810
model 0:npn_ae8 0:npn_ae8 0:npn_ae8 0:npn_ae8 0:npn_ae8 0:npn_ae8
ib 4.1914m 9.6267m 4.8851m 5.6241m 5.3776m 5.9637m
ic 325.5132u 2.8770m 4.5169m 1.9945m 3.4383m 2.2410m
vbe 3.2559 6.7176 4.6329 4.4121 1.8729 4.6496
vce 1.5156 6.7176 8.0945 4.4121 1.6522 4.8703
vbc 1.7404 0. -3.4617 0. 220.7678m -220.7678m
vs -5.8402 -4.2931 1.0756 1.2873 4.4579 6.0171
power 14.1402m 83.9949m 59.1942m 33.6142m 15.7524m 38.6432m
betad 77.6623m 298.8609m 924.6277m 354.6304m 639.3644m 375.7734m
gm 95.0412m 245.4902m 190.9493m 155.3525m 204.6854m 166.4518m
rpi 187.2846 50.1340 89.9376 104.5354 150.5519 94.8327
rx 283.3145 281.8993 283.0082 282.7463 71.6203 282.6425
ro 6.9408 5.4354 8.1624 6.6372 3.3389 6.5379
cpi 143.4111n 901.4620n 457.8518n 370.5332n 50.9725n 425.1933n
cmu 2.3758n 5.3411n 2.6953n 3.1518n 3.0513n 3.3361n
cbx 6.1274f 9.5695f 6.5686f 7.0396f 17.1097f 7.2551f
ccs 5.4332f 5.4332f 5.4332f 5.4332f 21.7326f 5.4332f
betaac 17.7998 12.3074 17.1735 16.2398 30.8158 15.7851
ft 68.5132k 19.1762k 4.1222k 22.9934k 5.9467k 20.4741k
"
So, you see the ib and ic!
kind regards,

 

[leo_o2]

Could you post your simulation schematic?
It is more readable.
Thanks.

 

[nanock]

hi,
this is the image of op-amp.
and notice to current source.the problem is "Ib>Ic" in q800-q810-q820-q830-q840-q850

 

[FvM]

The said transistors are apparently forming a bias generator. The circuit looks as strange as the transistor operation points. According to the vbe numbers, they are operated beyond any reasonable current related to the transistor area.
vbe 3.2559 6.7176 4.6329 4.4121 1.8729 4.6496

 

[nanock]

It is strange, but why it happens?
Why Ib > Ic ?